Made available in DSpace on 2014-06-11T19:33:39Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-05-11Bitstream added on 2014-06-13T19:04:52Z : No. of bitstreams: 1 almeida_tf_dr_jabo.pdf: 406856 bytes, checksum: ce8868f652409a4dd9a043c43a0b675e (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A mancha preta dos citros (MPC) doença causada pelo fungo Guignardia citricarpa Kiely [anamorfo: Phyllosticta citricarpa (McAlp.) Van der Aa], é a principal doença fúngica da cultura no Brasil. Todas as variedades de laranjeiras doces são suscetíveis ao patógeno, que deprecia comercialmente os frutos, além de provocar sua queda prematura e elevar substancialmente o custo de produção. Até o presente momento, informações acerca da etiologia da doença são escassas. Portanto, o presente trabalho teve como objetivos: determinar os tipos de sintomas expressos por G. citricarpa em frutos cítricos inoculados com suspensão de conídios; desenvolver uma metodologia de inoculação de G. citricarpa a qual seja eficiente e permita estabelecer relações qualitativa e quantitativa, tanto em termos de níveis de severidade e tipos de inóculo; determinar em casa de vegetação o período de suscetibilidade dos frutos de laranjeira ‘Pêra-Rio’ a G. citricarpa; verificar a influência da forma endofítica de G. mangifera na expressão de sintomas de G. citricarpa e; avaliar a relação da eficiência de controle químico da MPC versus o tempo de exposição dos frutos à descarga de conídios de G. citricarpa. Foi observado que G. citricarpa inoculada em suspensão conidial em frutos de laranjeira ‘Pêra-Rio’ produzem sintomas do tipo mancha dura, mancha sardenta, mancha virulenta e falsa melanose. Quando inoculada em frutos de tangor ‘Murcott’ produzem sintomas do tipo falsa melanose e mancha dura. Frutos de laranjeira ‘Pêra-Rio’ mostraram-se mais suscetíveis a G. citricarpa que o tangor ‘Murcott’. A metodologia de inoculação de conídios de G. citricarpa, mostrou-se eficiente, prática e rápida, permitindo quantificar o inóculo, fato inovador. Em relação à suscetibilidade, os frutos de laranjeira ‘Pêra-Rio’ quando inoculados... / Citrus black spot (CBS), caused by Guignardia citricarpa Kiely [anamorph: Phyllosticta citricarpa (McAlp.) Van der Aa], is of the most import citrus disease in Brazil. Practically, all varieties of sweet oranges are susceptible to pathogen, which depreciates commercially the fruits, causes drop prematurely and increase substantially the cost of production. Until now, information about the etiology of the disease is scarce. Therefore, this study aimed to determine the types of symptoms expressed by G. citricarpa in citrus inoculated with conidial suspension, to develop a method of inoculation with G. citricarpa which to be efficient and allow a qualitative and quantitative relations with levels of severity and inoculum types, to determine in greenhouse the period of susceptibility sweet orange fruits of 'Pêra-Rio' to G. citricarpa; the influence of endophytic form of G. mangiferae in the suppression of symptoms of G. citricarpa; and to evaluate the efficiency of chemical control of CBS vs exposure time of fruit to discharge of conidia of G. citricarpa. Conidia of G. citricarpa inoculated in sweet orange Pêra-Rio produced symptoms of the types: hard spot, freckled spot, virulent spot and false melanose. When conidia inoculated in ‘Murcott’ tangor fruits the symptoms were of the type false melanose hard spot. Sweet orange fruits showed more susceptible than ‘Murcott’ tangor. The methodology of inoculation of conidia used in this work showed very efficient and practice allowing discriminative studies related to the inoculum and, additional alternative to studies related to Citrus-G. citricarpa pathosystem. For the susceptibility, sweet orange fruits with 4.5 cm diameter, inoculated with G. citricarpa showed 56.94% of fruit with symptoms of MPC, 50% of fruits with 5.5 cm diameter and 27.75% when inoculated with ≥ 7 cm in diameter, is only... (Complete abstract click electronic access below)

Made available in DSpace on 2014-06-11T19:34:59Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-08-19Bitstream added on 2014-06-13T19:24:05Z : No. of bitstreams: 1 christovam_rs_dr_botfca.pdf: 504495 bytes, checksum: 175be209a6aecfa1989b2dd269f958d3 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Empresa Privada / Com o intuito de melhorar a eficiência de controle de Blumeria graminis Tritici e Puccinia Tritici na cultura do trigo, o presente trabalho objetivou avaliar diferentes técnicas de pulverização sobre os depósitos, controle de oídio e ferrugem da folha, bem como sobre a produtividade da cultura. Oito experimentos foram conduzidos na área experimental da FCA/UNESP – Campus de Botucatu, na cultura do trigo (cultivar IAC-370), sendo divididos em duas fases: quatro na área didática do Departamento de Produção Vegetal – Agricultura (Fase I) e quatro na área cascalheira (Fase II) na safra agrícola de 2009. O experimento 1 foi conduzido no delineamento em blocos ao acaso com 6 tratamentos e quatro repetições, totalizando 24 parcelas. Os tratamentos foram distribuídos no esquema fatorial 3 x 2 (três níveis de ar: 0, 15 e 29 km h-1 combinados a dois volumes de pulverização: 100 L ha-1 com pontas de jato plano XR 110015 e 200 L ha-1 com pontas de jato plano XR 11003). As parcelas foram dimensionadas em 8,0 x 10,0 m (largura x comprimento). De cada parcela foram selecionadas, ao acaso, 20 plantas para amostragem dos depósitos da pulverização. Para avaliação dos depósitos, foi utilizada uma substância marcadora (corante Azul Brilhante) na concentração de 0,15% do volume da calda de pulverização e a quantificação dos depósitos foi por espectrofotometria. O experimento 2 foi conduzido no mesmo local e os tratamentos distribuídos no mesmo delineamento do experimento anterior, acrescido da testemunha (plantas não tratadas). Nos estádios de desenvolvimento 32 (segundo nó visível) e 45 (emborrachamento completo) foram realizadas pulverizações com um fungicida triazol 2 (tebuconazole) à 100 e 200 L ha-1. A severidade das doenças oídio e ferrugem da folha foram avaliadas através... / In order to improve the control efficiency of Blumeria graminis Tritici and Puccinia Tritici in wheat crop, this study aimed to evaluate different spraying techniques on spray deposits, the control of wheat powdery mildew and wheat leaf rust, as well as crop productivity. In general, eight experiments were conducted at experimental area of FCA / UNESP - Botucatu city, in the wheat crop (IAC-370 variety) being divided into two steps: four experiments were carried out at experimental area of Plant Production - Agriculture Department (Step I) and others four experiments were performed at experimental area entitled Cascalheira (Step II) during 2009 season. The first experiment was carried out in randomized blocks with six treatments and four replications, totaling 24 plots. The treatments were arranged in a factorial scheme 3 x 2 (three air speed levels: 0, 15 and 29 km h-1 combined with two spray volumes 100 L ha-1 produced by flat fan nozzle XR 110 015 and 200 L ha-1 produced by flat fan nozzle XR 11003. The plots were dimensioned with 8.0 x 10.0 m (width x length). For each plot, it was selected 20 plants at random, which these plants were utilized to quantify spray deposits. For spray deposits evaluation, it was used a tracer substance (Brilliant Blue dye) in the 0.15% of spray volume concentration and the spray deposits quantification was made by spectrophotometer. The second experiment was carried out at the same place and the treatments were arranged in the same design from the previous experiment, plus a control treatment (untreated plants). In the growth stages 32 (second visible node) and stage 45 (complete boot), it was sprayed a triazol fungicide (tebuconazole) with... (Complete abstract click electronic access below)

Dissertação (mestrado)-Universidade Federal do Rio Grande, Programa de Pós-Graduação em Biologia de Ambientes Aquáticos Continentais, Instituto de Ciências Biológicas, 2012. / Submitted by Cristiane Gomides (cristiane_gomides@hotmail.com) on 2014-01-13T17:44:25Z No. of bitstreams: 1 0000010069.pdf: 1538365 bytes, checksum: c202c5228cc013b57b32fa76d75fad5d (MD5) / Approved for entry into archive by cristiane soares (krikasoares@live.com) on 2014-02-23T02:04:35Z (GMT) No. of bitstreams: 1 0000010069.pdf: 1538365 bytes, checksum: c202c5228cc013b57b32fa76d75fad5d (MD5) / Made available in DSpace on 2014-02-23T02:04:35Z (GMT). No. of bitstreams: 1 0000010069.pdf: 1538365 bytes, checksum: c202c5228cc013b57b32fa76d75fad5d (MD5) Previous issue date: 2012 / A contaminação de ambientes aquáticos por compostos potencialmente tóxicos oriundos de atividades agrícolas é um problema que tem se agravado nos últimos anos. O tebuconazol é um fungicida amplamente usado na agricultura, frequentemente encontrado em águas naturais, inclusive no Rio Grande do Sul, e cuja toxicidade para o fitoplâncton não é conhecida. O objetivo deste trabalho foi avaliar a toxicidade do tebuconazol em quatro espécies fitoplanctônicas dulcícolas subtropicais. Foram montadas culturas estanque em triplicata testando seis diferentes concentrações de tebuconazol (10; 100; 500; 1.000; 5.000 e 10.000 μg L-1) para Cosmarium depressum var. planctonicum, Desmodesmus communis, Pediastrum boryanum e Spondylosium pygmaeum, assim como um controle somente com a microalga, sem a adição do tebuconazol, para verificar o crescimento padrão. Os experimentos foram mantidos por 13 dias, nos quais foram realizadas amostragens diárias nos 4 primeiros dias e a cada 72 h até o final do experimento para a análise de crescimento (clorofila-a e densidade celular) e parâmetros toxicológicos. As quatro cepas apresentaram diferença significativa de crescimento em relação ao controle, para C. depressum var. planctonicum nas concentrações 5.000 e 10.000 μg L-1, D. communis e P. boryanum em 1.000, 5.000 e 10.000 μg L-1 e S. pygmaeum a partir de 500 μg L-1. A EC50 (concentração que inibe 50% do crescimento) foi de 3.616 μg L-1 para C. depressum var. planctonicum, 3.246 μg L-1 para D. communis, 3.863 μg L-1 para P. boryanum e 1.851 μg L-1 para S. pygmaeum, sendo o S. pygmaeum a cepa mais sensível. Para LOEC (concentração mais baixa com efeito observado) e NOEC (concentração mais alta sem efeito observado) S. pygmaeum também apresentou concentrações mais baixas, seguido de C. depressum var. planctonicum, D. communis e P. boryanum. / Public concern has increased regarding the uncontrolled use of pesticides, including fungicides. Tebuconazol is a broad-spectrum fungicide that is used worldwide; however, its toxicity to phytoplankton is unknown. This work aims to evaluate the tebuconazol influence on the growth of four subtropical freshwater phytoplanktonic strains. Experimental cultures of Cosmarium depressum var. planctonicum, Desmodesmus communis, Pediastrum boryanum and Spondylosium pygmaeum were prepared with six tebuconazol concentrations (10, 100, 500, 1.000, 5.000 and 10.000 μg L-1), besides a control that was also prepared to measure the regular growth of each microalgae. The cultures (triplicates) were maintained for 13 days to determine both the growth (cellular density and chlorophyll-a content) and toxicological parameters. Tebuconazol inhibited the growth of all phytoplanktonic strains when they were exposed to 5.000 and 10.000 μg L-1. D. communis and P. boryanum were also inhibited when exposed to 1.000 μg L-1, while S. pygmaeum was inhibited since 500 to 10.000 μg L-1. The calculated EC50 was 3.616 μg L-1 to C. depressum var. planctonicum, 3.246 μg L-1 to D. communis, 3.863 μg L-1 to P. boryanum and 1.851 μg L-1 to S. pygmaeum, that was the most sensible strain to tebuconazol. LOEC and NOEC were also lower to S. pygmaeum followed by C. depressum var. planctonicum, D. communis and P. boryanum.

Fungicides have been developed to protect plants against diseases and pests, which cause serious problems such as the loss of germination and vigour. The aim of this study was to test the germination and vigour of maize (Zea mays L.) seeds treated with several fungicides Apron® Star 42 WS (difenoconazole, thiamethoxam, and metalaxyl-m), Apron® XL (mefenoxam), Celest® XL (fludioxonil, mefenoxam) and thiram in the laboratory. In the greenhouse, the efficacy of fungicide treatment was evaluated in soil inoculated with Fusarium graminearum. The control consisted of untreated seeds. Germination and vigour were evaluated according to the International Seed Testing Association (1ST A) rules. The results from the standard gennination tests showed that all the fungicide treated seeds did not differ to the untreated control. The conductivity of solute leakage was read following slow and fast imbibition. Maize seeds treated with Apron® Star 42 WS, Celest® XL, Apron® XL and thiram improved or maintain vigour, which was indicated by a reduced or equivalent solute leakage following fast imbibition when compared with the untreated control. The good performance of fungicide treated seed expressed during conductivity test after fast imbibition correlated with the tetrazolium. All the fungicide treated seeds maintained the same viability as the untreated control following fast imbibition. After 6 h after fast imbibition, Apron® Star 42 WS, Celest® XL and Apron® XL treated seeds maintained similar germination percentages when compared to the untreated control with the exception of thiram treated seeds that exhibited a decline in seed viability. There was reduction in vigour in all the fungicide treated seeds fo llowing 24 and 40 h fast imbibition as illustrated by the reduction in germination percentage below the acceptable level (70%) when compared with the untreated control. The greenhouse study showed that all the fungicide treated seeds maintained the same emergence percentage in both inoculated and uninoculated soil with the exception of thiram treated seeds, where emergence improved in inoculated soil when compared to the untreated control. Apron® Star 42 WS and Celest® XL reduced the disease caused by F. graminearum in the inoculated soil. This study also revealed that the application of Apron® Star 42 WS, Celest® XL and thiram to seeds improved both the shoot and root dry mass of plants in the inoculated soil. / Dissertation (MInstAgrar)--University of Pretoria, 2011. / Microbiology and Plant Pathology / unrestricted

Orientador: Carlos Gilberto Raetano / Resumo: Fungicidas multi-sítio, a exemplo do mancozebe tem sido cada vez mais utilizados no controle da ferrugem da soja (Phakopsora pachyrhizi) e como estratégia anti-resistência aos fungicidas de sítio de ação único, amplamente utilizados na agricultura. Dessa maneira, buscou-se entender como a tecnologia de aplicação por meio da redução da taxa de aplicação e pelo uso de adjuvantes podem influenciar no controle da doença causada por Phakopsora pachyrhizi, quando associada ao fungicida mancozebe. Para isso, no capitulo 1, o objetivo foi avaliar a retenção foliar do fungicida de contato mancozebe em diferentes formulações na interação com adjuvantes em folhas de soja. No capítulo 2, o objetivo foi avaliar o controle da ferrugem da soja sob variação da taxa de aplicação de mancozebe em mistura com adjuvantes. Para a superfície adaxial a formulação GD apresenta maiores volumes de líquido retido enquanto que para a superfície abaxial, em geral, a formulação não apresenta interferência significativa. No geral, maior retenção da calda foi constatada na superfície abaxial do folíolo de soja, com destaque para caldas fungicidas contendo o polímero natural J-S e o óleo mineral Argenfrut. A redução da taxa de aplicação para 50 L ha-1 e a associação do fungicida mancozebe com adjuvantes pode influenciar a severidade da ferrugem da soja, contudo, de maneira geral, se considerar apenas a redução da taxa de aplicação, de 120 L ha-1 para 50 L ha-1, não há interferência no controle da doença, prin... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Multi-site fungicides as mancozebe has been increasingly used to control soybean rust (Phakopsora pachyrhizi) and as an anti-resistance strategy to single-site fungicides, widely used on agriculture. Thus, this study aimed a better understanding on how the application technology through the reduction of application rate and the use of adjuvants can influence on the control of the disease caused by Phakopsora pachyrhizi, in association with the fungicide mancozeb. To do so, on chapter 1 the study aimed to evaluate the foliar retention of mancozeb fungicide, in the WP and WG formulations, mixed with adjuvants on soybean leaves. On chapter 2, the aim of this study was to evaluate the soybean rust control under different volume rates of mancozeb spraying mixed with adjuvants. On the adaxial surface, the WG formulation has higher volumes of liquid retained while for the abaxial surface, in general, the formulation does not present significant interference. In most cases, greater retention of the spray mixture was found on the abaxial surface of the soybean leaflet, with emphasis on those containing the natural polymer J-S and the mineral oil Argenfrut. The reduction of the application rate to 50 L ha-1 and the association of the fungicide mancozebe with adjuvants can influence the severity of soybean rust, however, in general, if we consider only the reduction of the application rate, of 120 L ha-1 to 50 L ha-1, there is no interference in disease control, especially in early stag... (Complete abstract click electronic access below) / Mestre

Alternaria solani, cause of early blight, threatens potato yields. Fungicide resistance has made control of early blight difficult and there are concerns that in-season fungicide use results in resistance to boscalid, fluopyram, and chlorothalonil. Concern of high levels of resistance to boscalid a group 7 fungicide may confer cross-resistance to fungicides of the same group such as fluopyram. From 2014 to 2015, A. solani isolates were collected from field plots treated with boscalid, fluopyram, and chlorothalonil to test resistance levels. Isolates were determined resistant if EC50 values were higher than 5 µg ml-1. Boscalid and chlorothalonil mean EC50 values decreased two fold from 2014 to 2015, while fluopyram values increased two fold. A negative correlation between fluopyram and boscalid indicate no cross-resistance. Higher resistance levels to fluopyram (17.1 µg ml-1) were observed in the treatment C-14 where only fluopyram was applied in 2014. Treatments D-14 and D-15, only treated with chlorothalonil, had the highest mean EC50 values to chlorothalonil (2.3 and 1.1 µg ml-1, respectively). Field trials show fluopyram+chlorothalonil had lowest disease severity of 6.6 to 6.8%. Leaf residues of boscalid fluopyram, and chlorothalonil measured an average of 10.2, 4.9, and 55.0 ppm on leaves throughout the canopy. After 14 days average residues diminished to 0.74, 0.39, and 16.9 ppm for boscalid, fluopyram and chlorothalonil, respectively. Boscalid is not effective for early blight control because of high resistance; fluopyram resistance is increasing as treatments of fluopyram are applied; and chlorothalonil does not seem to be affected by continued fungicide application.

Soybean growers in the mid-southern U.S. face many challenges imposed by adverse weather conditions that vary spatially and temporally. As a result, growers experience variations in soybean seed quality, grain quality, and yield. While not every harvest season experiences extremes in environmental conditions, those that do may result in major quality issues that could lead to significant financial losses. Therefore, the objective of this research was to evaluate quality as it relates to delayed harvest conditions for soybean following common management practices such as fungicide application to mitigate spread of pathogens or harvest aid application to facilitate more efficient harvest. Experiments were conducted in 2019 and 2020 to determine the impact that these soybean management practices have on soybean quality under delayed harvest conditions. Results indicate that soybean quality, regardless of planting date, was not impacted by fungicide or harvest aid treatment, but rather by harvest delay.

Strawberry powdery mildew, caused by Podosphaera aphanis, affects leaves, fruit, and runners of strawberry plants. Infected leaves have reduced photosynthetic capability and infected fruit become unmarketable. Both of these factors translate to economic loss for the grower and therefore merit taking measures to control the disease. One objective of this study was to evaluate the resistance developed in populations of strawberry powdery mildew to chemical control measures. A fungicide assay was developed to evaluate the efficacy of six treatments (penthiopyrad, quinoxyfen, myclobutanil, trifloxystrobin, cyflufenamid, fluopyram + trifloxystrobin) for control of the disease. Nineteen isolates of strawberry powdery mildew were collected from Balico, Salinas, Watsonville, San Luis Obispo, Santa Maria, Ventura, and Oxnard CA and tested through the assay. The number of isolates resistant to each treatment was: penthiopyrad (7), quinoxyfen (6), myclobutanil (7), trifloxystrobin (2), cyflufenamid (1), fluopyram + trifloxystrobin (0). This documents resistance in P. aphanis to multiple chemicals used for its control. Documentation of any resistance is novel in California and novel worldwide with resistance to Fungicide Resistance Action Committee (FRAC) codes 7 and 13. Another objective of this study was to evaluate host plant resistance to strawberry powdery mildew. Twelve cultivars were evaluated in a winter greenhouse trial, sixteen cultivars in a summer greenhouse trial, and the ten cultivars shared in both trials were also evaluated in two fields. The cultivars found to be most susceptible to mildew infection were BG 3.324 and Royal Royce. The cultivars found to be the least susceptible to mildew infection were Fronteras, San Andreas, and Sweet Ann. The cultivars evaluated represent more than 55% of the state’s acreage and the host plant resistance information will be a valuable tool to growers looking to culturally control powdery mildew.

The effectiveness of the biocontrol product Actinovate® at enhancing tomato plant growth and yield, and reducing the presence of fungal pathogens was studied in greenhouse and field conditions. In the greenhouse, no differences were found among seed germination or plant survival rates, seedling heights, dry root weights, and dry shoot weights of tomato seedlings grown from seeds drenched with Actinovate® or Rootshield®. The effects of one initial Actinovate® seed drench at sowing, repeated applications through the drip irrigation throughout the season, or repeated applications through the drip irrigation plus foliar applications throughout the season at reducing plant infection by fungal plant pathogens, and increasing yield and quality for tomato plants (Solanum lycopersicum) were investigated in Los Alamos, CA, on a sandy loam soil. No significant differences in plant height were found among the four treatments. Marketable fruit weight was greater in the drip plus foliar treatment than in the Actinovate® seed drench treatment. The foliar plus drip treatment resulted in the greatest amount of powdery mildew present, although the disease pressure was low. No significant differences were found among the four treatments in the presence of Verticillium wilt or Sclerotinia.

Southern Blight (SB), caused by the fungus Athelia rolfsii, has increasingly impacted Mississippi soybean production with estimated economic losses in recent years rising from $181,616 in 2016 to $9,508,412 in 2021. Currently, there are no recommended fungicides and no known commercially available cultivar resistance. Eleven cultivars were evaluated for their response to the presence of Athelia rolfsii in the 2021 field trial. An in vitro fungicide assay was conducted to evaluate the efficacy of five fungicides to determine the respective EC50. These fungicides were then evaluated in combination with three cultivars, one mild, one moderate, and one severe in the 2022 field trial and in the growth chamber trial. A rapid and quantitative method was developed to evaluate the response of these commercially available soybean cultivars in combination with fungicides to SB. Determining effective management options has the potential to decrease disease losses for Mississippi Soybean growers.